A heightened propensity for risk-taking and poor decision-making underlies the peak morbidity and mortality rates reported during adolescence. Delayed maturation of cortical structures during the ...adolescent years has been proposed as a possible explanation for this observation. Here, we test the hypothesis of adolescent delayed maturation by using fMRI during a monetary decision-making task that directly examines risk-taking behavior during choice selection. Orbitofrontal/ventrolateral prefrontal cortex (OFC/VLPFC) and dorsal anterior cingulate cortex (ACC) were examined selectively since both have been implicated in reward-related processes, cognitive control, and resolution of conflicting decisions. Group comparisons revealed greater activation in the OFC/VLPFC (BA 47) and dorsal ACC (BA 32) in adults than adolescents when making risky selections. Furthermore, reduced activity in these areas correlated with greater risk-taking performance in adolescents and in the combined group. Consistent with predictions, these results suggest that adolescents engage prefrontal regulatory structures to a lesser extent than adults when making risky economic choices.
Many changes in social behavior take place during adolescence. Sexuality and romantic interests emerge during this time, and adolescents spend more time with peers and less time with parents and ...family. While such changes in social behavior have been well documented in the literature, relatively few neurophysiological explanations for these behavioral changes have been presented.
In this article we selectively review studies documenting (a) the neuronal circuits that are dedicated to the processing of social information; (b) the changes in social behavior that take place during adolescence; (c) developmental alterations in the adolescent brain; and (d) links between the emergence of mood and anxiety disorders in adolescence and changes in brain physiology occurring at that time.
The convergence of evidence from this review indicates a relationship between development of brain physiology and developmental changes in social behavior. Specifically, the surge of gonadal steroids at puberty induces changes within the limbic system that alters the emotional attributions applied to social stimuli while the gradual maturation of the prefrontal cortex enables increasingly complex and controlled responses to social information.
Observed alterations in adolescent social behavior reflect developmental changes in the brain social information processing network. We further speculate that dysregulation of the social information processing network in this critical period may contribute to the onset of mood and anxiety disorders during adolescence.
Adolescence is associated with maturation of function within neural networks supporting the processing of social information. Previous longitudinal studies have established developmental influences ...on youth's neural response to facial displays of emotion. Given increasing recognition of the importance of non-facial cues to social communication, we build on existing work by examining longitudinal change in neural response to vocal expressions of emotion in 8- to 19-year-old youth. Participants completed a vocal emotion recognition task at two timepoints (one year apart), while undergoing functional magnetic resonance imaging. The right inferior frontal gyrus, right dorsal striatum, and right precentral gyrus showed decreases in activation to emotional voices across timepoints, which may reflect focalization of response in these areas. Activation in the dorsomedial prefrontal cortex was positively associated with age, but was stable across timepoints. In addition, the slope of change across visits varied as a function of participants' age in the right temporo-parietal junction (TPJ): this pattern of activation across timepoints and age may reflect ongoing specialization of function across childhood and adolescence. Decreased activation in the striatum and TPJ across timepoints was associated with better emotion recognition accuracy. Findings suggest that specialization of function in social cognitive networks may support the growth of vocal emotion recognition skills across adolescence.
Background Diarrheal disease is a leading cause of morbidity and mortality globally, especially in low- and middle-income countries. High-throughput and low-cost approaches to identify etiologic ...agents are needed to guide public health mitigation. Nanoliter-qPCR (nl-qPCR) is an attractive alternative to more expensive methods yet is nascent in application and without a proof-of-concept among hospitalized patients. Methods A census-based study was conducted among diarrheal patients admitted at two government hospitals in rural Bangladesh during a diarrheal outbreak period. DNA was extracted from stool samples and assayed by nl-qPCR for common bacterial, protozoan, and helminth enteropathogens as the primary outcome. Results A total of 961 patients were enrolled; stool samples were collected from 827 patients. Enteropathogens were detected in 69% of patient samples; More than one enteropathogen was detected in 32%. Enteropathogens most commonly detected were enteroaggregative Escherichia coli (26.0%), Shiga toxin-producing E.coli (18.3%), enterotoxigenic E. coli (15.5% heat stable toxin positive, 2.2% heat labile toxin positive), Shigella spp. (14.8%), and Vibrio cholerae (9.0%). Geospatial analysis revealed that the median number of pathogens per patient and the proportion of cases presenting with severe dehydration were greatest amongst patients residing closest to the study hospitals." Conclusions This study demonstrates a proof-of-concept for nl-qPCR as a high-throughput low-cost method for enteropathogen detection among hospitalized patients.
Over the last several years a number of studies in both humans and animals have suggested that the orbitofrontal and ventrolateral prefrontal cortices play an important role in generating flexible ...behavior. We suggest that input from these brain regions contribute to three functions involved in generating flexible behavior within social contexts: valuation, inhibition, and rule use. Recent studies have also demonstrated that the prefrontal cortex undergoes a prolonged course of maturation that extends well after puberty. Here, we review evidence that the prolonged development of these prefrontal regions parallels a slowly emerging ability for flexible social behavior. We also speculate on the possibility that sensitive periods for organizing social behavior may be embedded within this developmental time-fame. Finally, we discuss the role of prefrontal cortex in adolescent mood and anxiety disorders, particularly as orbitofrontal and ventrolateral prefrontal cortices are engaged in a social context.
Sensitivity to social evaluation has been proposed as a potential marker or risk factor for depression, and has also been theorized to increase with pubertal maturation. This study utilized an ...ecologically valid paradigm to test the hypothesis that adolescents with major depressive disorder (MDD) would show altered reactivity to peer rejection and acceptance relative to healthy controls in a network of ventral brain regions implicated in affective processing of social information. A total of 48 adolescents (ages 11-17), including 21 with a current diagnosis of MDD and 27 age- and gender-matched controls, received rigged acceptance and rejection feedback from fictitious peers during a simulated online peer interaction during functional neuroimaging. MDD youth showed increased activation to rejection relative to controls in the bilateral amygdala, subgenual anterior cingulate, left anterior insula and left nucleus accumbens. MDD and healthy youth did not differ in response to acceptance. Youth more advanced in pubertal maturation also showed increased reactivity to rejection in the bilateral amygdala/parahippocampal gyrus and the caudate/subgenual anterior cingulate, and these effects remained significant when controlling for chronological age. Findings suggest that increased reactivity to peer rejection is a normative developmental process associated with pubertal development, but is particularly enhanced among youth with depression.
The spermosphere represents a short-lived, rapidly changing, and microbiologically dynamic zone of soil surrounding a germinating seed. It is analogous to the rhizosphere, being established largely ...by the carbon compounds released into the soil once the seed begins to hydrate. These seed exudations drive the microbial activities that take place in the spermosphere, many of which can have long-lasting impacts on plant growth and development as well as on plant health. In this review, I discuss the nature of the spermosphere habitat and the factors that give rise to its character, with emphasis on the types of microbial activities in the spermosphere that have important implications for disease development and biological disease control. This review, which represents the first comprehensive synthesis of the literature on spermosphere biology, is meant to illustrate the unique nature of the spermosphere and how studies of interactions in this habitat may serve as useful experimental models for testing hypotheses about plant-microbe associations and microbial ecology.
Hourly samples of tertiary wastewater effluent were analyzed for 30 pharmaceuticals, personal care products, estrogenic steroids, and alkylphenols in order to better understand the rate at which ...these compounds enter the environment. Several distinct patterns of daily cycling were observed, and were characterized as three separate categories. The concentrations of compounds such as trimethoprim, sulfamethoxazole, naproxen, estrone, and triclosan varied greatly during a daily cycle, with relative standard deviations exceeding 100% of their daily mean. Less extreme daily cycles were seen for other compounds such as azithromycin, atenolol, tert-octylphenol, iopromide and gemfibrozil. Peak concentrations for most compounds occurred in the early evening (5−8 pm). However, some compounds including carbamazepine, primidone, fluoxetine, and triclocarban exhibited little or no variability.
Many transgender adolescents experience clinically elevated anxiety and depression. Testosterone (T), used as a gender affirming treatment, may reduce symptoms of anxiety and depression. We assessed ...the effect of gender affirming T treatment on internalizing symptoms, body image dissatisfaction, and activation patterns within the amygdala-prefrontal cortex circuit in transgender adolescent boys.
Symptoms of generalized anxiety, social anxiety, depression, suicidality and body image dissatisfaction were measured by self-report and brain activation was measured during a face processing task with functional MRI in a group of 19 adolescent transgender boys receiving T treatment and 23 not receiving gonadal hormone treatment (UT).
Severity of anxiety and depression was significantly lower in the T treated group relative to the UT group, along with a trend of lower suicidality. The T group also reported less distress with body features and exhibited stronger connectivity within the amygdala-prefrontal cortex circuit compared to the UT group. Finally, group differences on depression and suicidality were directly associated with body image dissatisfaction, and anxiety symptoms were moderated by amygdala-prefrontal cortex connectivity differences between groups.
T treatment is associated with lower levels of internalizing symptoms among transgender adolescent boys. T is also associated with greater body satisfaction and greater connectivity in a neural circuit associated with anxiety and depression. Satisfaction with body image was found to overlap with the association between T and both depression and suicidality, and amygdala-prefrontal co-activation moderated the role of T on anxiety.
•Testosterone treated transgender youth have reduced internalizing symptoms.•Testosterone associated with improved body image satisfaction in transgender youth.•Testosterone associated with stronger amygdala-prefrontal cortex co-activation.
Abstract
Background
Converging lines of evidence point to hippocampal dysfunction in psychosis spectrum disorders, including altered functional connectivity. Evidence also suggests that antipsychotic ...medications can modulate hippocampal dysfunction. The goal of this project was to identify patterns of hippocampal connectivity predictive of response to antipsychotic treatment in 2 cohorts of patients with a psychosis spectrum disorder, one medication-naïve and the other one unmedicated.
Hypothesis
We hypothesized that we would identify reliable patterns of hippocampal connectivity in the 2 cohorts that were predictive of treatment response and that medications would modulate abnormal hippocampal connectivity after 6 weeks of treatment.
Study Design
We used a prospective design to collect resting-state fMRI scans prior to antipsychotic treatment and after 6 weeks of treatment with risperidone, a commonly used antipsychotic medication, in both cohorts. We enrolled 44 medication-naïve first-episode psychosis patients (FEP) and 39 unmedicated patients with schizophrenia (SZ).
Study Results
In both patient cohorts, we observed a similar pattern where greater hippocampal connectivity to regions of the occipital cortex was predictive of treatment response. Lower hippocampal connectivity of the frontal pole, orbitofrontal cortex, subcallosal area, and medial prefrontal cortex was predictive of treatment response in unmedicated SZ, but not in the medication-naïve cohort. Furthermore, greater reduction in hippocampal connectivity to the visual cortex with treatment was associated with better clinical response.
Conclusions
Our results suggest that greater connectivity between the hippocampus and occipital cortex is not only predictive of better treatment response, but that antipsychotic medications have a modulatory effect by reducing hyperconnectivity.
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